Reduced embolic load during clinical cardiopulmonary bypass using a 20 micron arterial filter.

OBJECTIVE: To compare the efficiency of 20 and 40 µm arterial line filters during cardiopulmonary bypass for the removal of emboli from the extracorporeal circuit. METHODS: Twenty-four adult patients undergoing surgery were perfused using a cardiopulmonary bypass circuit containing either a 20 µm or 40 µm arterial filter (n = 12 in both groups). The Emboli Detection and Classification system was used to count emboli upstream and downstream of the filter throughout cardiopulmonary bypass. The mean proportion of emboli removed by the filter was compared between the groups. RESULTS: The 20 µm filter removed a significantly greater proportion of incoming emboli (0.621) than the 40 µm filter (0.334) (p=0.029). The superiority of the 20 µm filter persisted across all size groups of emboli larger than the pore size of the 40 µm filter. CONCLUSION: The 20 µm filter removed substantially more emboli than the 40 µm filter during cardiopulmonary bypass in this comparison.

Pneumolabyrinth: a late complication of stapes surgery.

As temporal bone imaging techniques continue to improve, it is likely that we will see an increase in the detection of pneumolabyrinth. Several mechanisms have been proposed to explain how air enters the labyrinth. A small number of authors has reported an association between pneumolabyrinth and temporal bone fractures, perilymphatic fistulae, and displaced stapes prostheses. In this article, we describe a new case of pneumolabyrinth that was seen as a late complication of stapes surgery, and we summarize what is known about this rare condition.

Xanthoma of the temporal bone: a unique case of this rare condition.

Xanthoma of the temporal bone is extremely rare; we describe only the fourteenth reported case. Our case is further remarkable because it is the first report of such an occurrence in a patient with familial type III hyperlipoproteinemia. Moreover, while otalgia, infection, hearing loss, and tinnitus were the most common initial symptoms in the previous 13 cases, our patient reported only diplopia, vertigo, and unstable gait. The patient underwent a simple mastoidectomy and debulking, and his diplopia, vertigo, and unstable gait resolved.

Endoscopic repair of cerebrospinal fluid rhinorrhea.

Endoscopic repair of cerebrospinal fluid rhinorrhea is a promising alternative to traditional repair techniques. This article reports our experience with 21 cases (10 spontaneous, 8 iatrogenic, and 3 traumatic). Various diagnostic radiographic modalities were used, including computer-aided techniques. Most repairs were accomplished with a free fascial graft positioned in the epidural space. Postoperative lumbar drainage was used in 15 cases. Initial repair was successful in 18 cases (85.7%). In all 3 failures, the surgeon had difficulty with proper graft placement. Additionally, 2 of these cases were confounded by early inadvertent removal of the lumbar drain. All patients in whom the procedure failed underwent a second successful endoscopic repair. There were no major complications. In our experience endoscopic repair of cerebrospinal fluid rhinorrhea is a safe and effective approach that can be improved with computer-aided localization devices. Proper graft placement is critical, and lumbar drainage is an important adjunct in selected cases.

Upper limb free flap reconstruction after tumor resection.

Free tissue transfer is the autologous transplantation of composite tissue and its arterial and venous blood supply to a distant site. Free tissue transfers, also called free flaps, may include skin, fascia, muscle, or bone. Free flaps were once considered highly complex procedures; now they are frequently used as the reconstructive option of choice. While several variables must be considered when one plans a free tissue transfer, the most important consideration is the size and location of the defect created by the tumor resection. Free tissue transfer is a multistep procedure, including preparation of the recipient site, harvesting of the flap, and transfer and revascularization of the flap. For upper extremity reconstruction, the gracilis muscle flap has been particularly useful, as has the lateral arm fasciocutaneous flap. Semin. Surg. Oncol. 19:246-254, 2000.

Hemangioma of the spleen: presentation, diagnosis, and management.

Splenic hemangioma is a rare disorder but remains the most common benign neoplasm of the spleen. It often has a latent clinical picture; however, spontaneous rupture has been reported to occur in as many as 25% of this patient population.1 Treatment most often consists of splenectomy. This report reviews an 8-year experience with splenic hemangioma at Mayo Clinic. Thirty-two patients were identified with SH during the 8-year study period. The average age was 63 years (range 23 to 94 years) with 17 women and 15 men. Six patients presented with symptoms potentially related to the SH. The remainder (80%) were asymptomatic, and the SH was discovered incidentally during evaluation for other disorders. A mass or palpable spleen was appreciated in only four patients (12.5%). SHs ranged in size from 0.3 to 7 cm maximum diameter. A diagnosis of SH was made in 11 patients based on the findings of a splenic mass on computed tomography or ultrasound. Each of these SHs was < or =4 cm. Three of the 11 patients had multiple SHs. All 11 patients were managed successfully with observation. All but one of the patients remains asymptomatic, and no complications have developed during follow-up (range 0.6 to 7 years, mean 2.9 years). The diagnosis of splenic hemangioma was made at the time of surgery in the remaining 21 patients (65%). Splenectomy was performed for suspicion of primary or secondary splenic pathology. There were no instances of spontaneous rupture of the SH. Small splenic lesions, which meet the radiologic criteria for hemangiomas, may be safely observed.

Intraoperative facial nerve monitoring: a comparison between electromyography and mechanical-pressure monitoring techniques.

OBJECTIVES: To examine the hypothesis that for intraoperative facial nerve monitoring, an EMG monitor is more sensitive than a mechanical-pressure monitor. To compare the threshold sensitivity of the two facial nerve monitoring methods-mechanical-pressure versus EMG--by using them simultaneously during surgery. To assess and compare their true- and false-positive responses in otologic and neurotologic procedures. SETTING: A tertiary referral private otology/neurotology practice. STUDY DESIGN: Prospective case-controlled study. PATIENTS AND METHODS: The facial nerve of 46 consecutive patients undergoing various otologic and neurotologic procedures was stimulated intraoperatively using a pulsed constant-current. Facial responses were monitored using the Silverstein WR-S8 Monitor/Stimulator and the Brackmann EMG System simultaneously. The threshold (i.e., minimal) current level required to elicit a response from each monitor was recorded. Monitor responses to facial nerve manipulation (including false-positive responses) were assessed by continuous recording of all responses, using the Wiegand Monitoring System, and noting the causative event for each response. RESULTS: The EMG monitor responded to lower current threshold (p < 0.001) in every surgical procedure and for every nerve segment studied. However, the average threshold difference was <0.05 mAmps and in clinical practice, when using above threshold stimulation, becomes negligible. In posterior fossa surgery, the EMG monitor showed higher sensitivity by responding earlier to various manipulations of the bare facial nerve. The EMG had more false-positive responses than the mechanical-pressure monitor. CONCLUSIONS: In otologic surgery, if monitoring is required, the mechanical-pressure monitor is used. In neurotologic surgery, both monitors are used simultaneously.

Venous air in the bypass circuit: a source of arterial line emboli exacerbated by vacuum-assisted drainage.

BACKGROUND: Arterial emboli cause neurocognitive deficits in cardiac surgical patients. Carotid artery emboli, detected ultrasonically, have been observed after venous air entrainment into the cardiopulmonary bypass circuit. We investigated in vitro the extent to which venous air affected emboli detected in the arterial line downstream from a 40-microm filter. METHODS: Using salvaged clinical cardiopulmonary bypass circuits, fixed volumes of air were introduced into the venous return line at unrestricted rates and at fixed rates using gravity venous drainage and vacuum-assisted venous drainage. Emboli counts were recorded distal to the arterial line filter using a 2-MHz pulsed-wave Doppler monitor. Emboli counts were similarly recorded after the introduction of carbon dioxide into the venous return line instead of air. RESULTS: The number of emboli rose with increasing volumes of entrained venous air (p < 0.001), and there was an almost tenfold increase with vacuum-assisted venous drainage (p < 0.0001) compared with gravity venous drainage. Venous air was entrained at a significantly faster rate under vacuum-assisted venous drainage (p < 0.0001). When the entrainment rate of venous air was fixed, the difference in emboli numbers recorded for gravity and assisted venous drainage was not significant. There was a significant reduction in arterial line emboli when carbon dioxide rather than air was entrained under both vacuum-assisted and gravity drainage (p < 0.001). CONCLUSIONS: Entrained venous air during cardiopulmonary bypass is a potential hazard, particularly during vacuum-assisted venous drainage. Every effort should be made to avoid venous air entrainment.

A reevaluation of the 512-Hz Rinne tuning fork test as a patient selection criterion for laser stapedotomy.

OBJECTIVE: This study aimed to challenge the classical hypothesis that a negative preoperative 512-Hz Rinne tuning fork test (bone conduction greater than air conduction) is a necessary condition to allow consistent objective and subjective hearing improvement with surgery for otosclerosis. STUDY DESIGN: The study design was retrospective (chart review and questionnaire). SETTING: The study was conducted at a Florida Ear and Sinus Center at Sarasota, Florida, a tertiary otology-neurotology referral center. PATIENTS: Patients who underwent primary laser stapedotomy with equivocal (air=bone) preoperative 512-Hz Rinne test results participated. INTERVENTION: KTP laser stapedotomy was performed. MAIN OUTCOME MEASURES: Audiologic measurements of air-bone gap closure and patient assessment of hearing improvement and satisfaction were conducted. RESULTS: The air-bone gap was closed to within 10 dB in all cases. There were no complications. Eighteen patients were questioned about their results. Hearing improvement was subjectively described as "excellent" or "good" by 17 (94%), and 16 (89%) thought the surgery was "absolutely" worthwhile. CONCLUSIONS: The preoperative 512-Hz Rinne test results need not be negative to achieve significant air-bone gap closure and subjective appreciation of improved hearing.

Bubble generation and venous air filtration by hard-shell venous reservoirs: a comparative study.

We have previously shown significant bubble formation in Medtronic Maxima hard-shell venous reservoirs (HSVRs). In the present study, we not only investigated the mechanism of this bubble formation, but also the extent of bubble clearance by membrane oxygenators and arterial line filters. In addition, we also compared the performance of five HSVRs with respect to bubble formation and venous air filtration. Salvaged clinical CPB circuits containing different HSVRs were studied by downstream Doppler monitoring under fixed flow-decreasing volume, fixed volume-increasing flow, and entrained venous air conditions. Bubbles formed in the Medtronic Maxima top entry HSVR at volumes below 800 ml and flows above 3.5 l min-1, and were incompletely removed by a membrane oxygenator and arterial line filter. Decreased bubbling was seen when the reservoir atmosphere was flushed with CO2, suggesting that these bubbles formed in a fountain at the venous inflow. The Medtronic Maxima Forte HSVR formed significantly fewer bubbles at low volumes, and filtered venous air effectively. Negligible bubble formation occurred in the Sorin, Terumo, or Baxter reservoirs. The minimum recommended operating volume for the Medtronic Maxima top entry reservoir should be reset at 600 ml and this device should always be used with an arterial filter. Bubble formation is substantially reduced in the new Medtronic Maxima Forte HSVR and this device is a good filter for venous air.

Abnormal IL-4 gene expression by atopic dermatitis T lymphocytes is reflected in altered nuclear protein interactions with IL-4 transcriptional regulatory element.

Among the atopic disease, atopic dermatitis is characterized by the highest levels of serum IgE and by increased peripheral blood T-cell interleukin-4 (IL-4) production. IL-4 promotes IgE synthesis by B cells and stimulates the growth of IL-4-producing T cells and may contribute to the pathogenesis of this disease. In this study, in situ hybridization established that atopic dermatitis patients have a higher frequency of IL-4-producing peripheral blood T cell when compared to normal subjects. These in vivo-derived T cells were used to examine the signaling requirements of IL-4 production and the nuclear factors that associate with a critical IL-4 transcriptional regulatory element between -88 and -60 relative to the IL-4 transcription initiation site, the activation responsive element. We demonstrate that, as in T-cell lines, proteins belonging to the NF-AT and AP-1 family of transcription factors are present in stimulated cell extracts and specifically associate with the activation responsive element. Dysregulated IL-4 production is reflected in the nuclear proteins that associated this element. Using gel shift assays, we found that 12 of 12 nuclear extracts from stimulated atopic T cells formed the activation-dependent protein-DNA complex, compared to only 2 of 12 normal T-cell extracts. Activation complex formation correlated with the relative level of IL-4 mRNA and protein produced in stimulated T cells, suggesting that abnormal IL-4 gene expression in atopic disease may be linked to alterations in nuclear protein interactions with these promoter elements.

Emboli generation by the Medtronic Maxima hard-shell adult venous reservoir in cardiopulmonary bypass circuits: a preliminary report.

Increases in right common carotid artery Doppler ultrasound signals typical of emboli were found in cardiopulmonary bypass patients when the Medtronic Maxima hard-shell adult combined venous and cardiotomy reservoir was operated at reservoir blood volumes near the manufacturer;s recommended minimum of 300 ml. The signals were reduced by increasing the reservoir blood volume. Possible microembolus generation in the top- and bottom-entry versions of this reservoir was investigated using an in vitro circuit and a colour flow Doppler monitor that was interfaced with a microprocessor to count the signals. The reservoir blood volume was progressively lowered in 100 ml increments below 1000 ml, and signals were counted over five minutes at each new level. Signal counts downstream of the reservoir increased exponentially after the volume was decreased below 1000 ml in the bottom-entry version, and 700 ml in the top-entry version. Ultrasonic monitoring, both upstream and downstream of the reservoir, showed that the source of these signals was the reservoir itself, and that recirculation of emboli around the circuit accounted for only a small proportion of the measured increase. Changes in circuit blood prime haematocrit within the range 0.11-0.31 did not alter the signal counts. However, counts were profoundly affected by exposure of the circuit to nitrous oxide via a membrane oxygenator; this showed that the emboli were bubbles. Bubble formation may occur where venous blood enters the reservoir as this results in a fountaining effect when the reservoir volume is low. This effect appears to have been serendipitously reduced, but not eliminated, in the design of the top-entry version. It is recommended that perfusionists should not operate these reservoirs at volumes below 1000 and 700 ml in the bottom- and top-entry versions respectively.

Lightning injury of the tympanic membrane.

Lightning injury to the ear is known, but specific reports are lacking. Four patients with tympanic membrane perforations who were managed surgically are reported. Their presentations, evaluations, intraoperative findings, and outcomes are discussed as they relate to the proposed pathogenic mechanisms. The authors' standard wide exposure tympanoplasty approach with two layer tympanic membrane repair is described. The added steps in performing this procedure may be necessary to ensure a good result in this unique group of patients.

The jugular dural fold-a helpful skull base landmark to the cranial nerves.

During a retrosigmoid (or combined retrolabyrinthine-retrosigmoid) approach to the posterior fossa for vestibular neurectomy or removal of small acoustic neuromas, a white dural fold is a consistent landmark to cranial nerves VII through XII. This fold of dura appears as a white linear structure extending from the foramen magnum across the sigmoid sinus, attaching to the posterior aspect of the temporal bone, anterior to the vestibular aqueduct. The name "jugular dural fold" is suggested for this landmark. The jugular dural fold overlies the junction of the sigmoid sinus and the jugular foramen. As measured in formalin-fixed cadaver heads, the overall length of the jugular dural fold is 20.8 mm (+/- 2.9 mm). The cochleovestibular nerve lies 9.9 mm (+/- 1.5 mm) anterior to the superior aspect of the jugular dural fold, the glossopharyngeal nerve lies 9.5 mm (+/- 1.6 mm) anterior to the midpoint of the jugular dural fold, and the operculum of the vestibular aqueduct lies 6.6 mm (+/- 0.7 mm) posterior to the jugular dural fold. Intraoperative measurements in patients undergoing combined retrolabyrinthine-retrosigmoid vestibular neurectomy show an overall length of the jugular dural fold of 16.3 mm (+/- 1.9 mm). The cochleovestibular nerve lies 8.6 mm (+/- 1.3 mm) anterior to the superior aspect of the jugular dural fold, the glossopharyngeal nerve lies 8.6 mm (+/- 1.3 mm) anterior to the midpoint of the jugular dural fold, and the operculum lies 7.5 mm (+/- 0.8 mm) posterior to the jugular dural fold. The jugular dural fold can be used as a reliable landmark for rapidly locating cranial nerves in the posterior fossa.

Otologic manifestations of neurofibromatosis.

A chart review of 440 patients with neurofibromatosis seen at the Children's Hospital of Philadelphia Neurofibromatosis Clinic between 1980 and 1991 was performed to look for otologic manifestations. Neurofibromatosis 1 was present in 434 patients, and neurofibromatosis 2 was present in 6. A total of 31 otologic abnormalities related to neurofibromatosis were found in 28 patients. Neurofibromas of the external ear, including the pinna and the external auditory canal, were the most common finding. Middle ear neurofibromas were found in two patients. Acoustic neuromas were seen exclusively in patients believed to have neurofibromatosis 2. One cerebellopontine angle neurofibrosarcoma was found in a patient with neurofibromatosis 1.

Prediction of facial nerve function following acoustic neuroma resection using intraoperative facial nerve stimulation.

Methods of monitoring the facial nerve during posterior fossa surgery continue to evolve. In an effort to predict acute and final facial nerve function following acoustic neuroma resection, the lowest current applied to the facial nerve at the brainstem necessary to elicit facial muscle response was measured using strain gauge and electromyographic facial nerve monitors. A retrospective analysis of 121 patients who had undergone acoustic neuroma surgery was performed. Sixty-five patients had intraoperative facial nerve monitoring and 44 had sufficient data for inclusion in this study. The acute and final facial nerve functions, according to the House-Brackmann classification, were assessed with regard to intraoperative stimulation-current thresholds. Nineteen of 20 patients who required 0.10 mA or less to elicit a facial muscle response had a House-Brackmann grade I facial nerve outcome. The upper limit of the 95% confidence interval of stimulation threshold for patients with a final grade I facial nerve function is 0.17 mA. All of the patients in this study, with stimulation thresholds ranging up to 0.84 mA, had a final grade III or better result. A poor outcome in our series, a final grade III facial nerve function, is best predicted by a poor acute result, specifically an acute grade VIA facial nerve function. We suggest that it is possible to predict the facial nerve function based on intraoperative threshold testing.

Vestibular nerve section.

In the nearly 90 years since Frazier first performed an eighth nerve section through the posterior fossa for the treatment of Ménières's disease, the surgical management of Ménière's disease has come full circle. With refinements in surgical technique and advancements in instrumentation, optics, illumination, and neuromonitoring, a procedure that was once resoundingly condemned by the otologic community is now regarded as the procedure of choice in patients with serviceable hearing. The vestibular nerve section has experienced a renaissance. The posterior fossa vestibular nerve section has undergone an evolution, and the combined retrolabyrinthine-retrosigmoid vestibular nerve section represents the highest form. It is a significant improvement over its predecessors and our procedure of choice in properly selected patients.